The geopolymeric alumino-silicates have been grouped in three families depending on the atomic ratio Si/Al which may be 1, 2 or 3. With the most commonly used simplified notation, a distinction is made between
__________________________________________________________________________ poly(sialate) M.sub.n (--Si--O--Al--O--).sub.n or (M)-PS, poly(sialate-siloxo) M.sub.n (--Si--O--Al--O--Si--O--).sub.n or (M)-PSS, poly(sialate-disiloxo) M.sub.n (--Si--O--Al--O--Si--O--Si--O--).sub.n or (M)-PSDS. __________________________________________________________________________
In several scientific papers, for instance "Geopolymer: room temperature ceramic matrix composites" published in Ceram. Eng. Sci. Proc., 1988, Vol. 9 (7-8), pp. 835-41, cf. Chemical Abstracts 110-080924, or "Geopolymer Chemistry and Properties" published in Geopolymer '88, Vol. 1, pp. 18-23, University ,of Technology, Compiegne, France, and the international patent publication WO 88/02741 (U.S. Pat. No. 4,888,311), the prior art discloses the uses of
poly(sialate)Mn(--Si--O--Al--O),(Na)--PS/(K)--PS and PA0 poly(sialate-siloxo)Mn(--Si--O--Al--O--Si--O--),(nA)--PSS/(K)--PSS. PA0 poly(sialate-disiloxo)Mn(--Si--O--Al--O--Si--O--Si--O--)n,(M)--PSDS. PA0 poly(sialate-disiloxo) Mn(--Si--O--Al--O--S--O--Si--O--)n,(M)--PSDS. PA0 (M)-PSDS, i.e. Mn(--Si--O--Al--O--Si--O--Si--O--), with the ratio Si/Al.gtoreq.3 PA0 (M)-PSS, i.e. Mn(--Si--O--Al--O--Si--O--), with the ratio Si/Al=2 and PA0 (M)-PS, i.e. Mn(--Si--O--Al--O--), with the ratio Si/Al=1. PA0 poly(sialate-disiloxo) Mn(--Si--O--Al--O--Si--O--Si--O--)n,(M)-PSDS,
It does not deal with any process for producing,
Our corresponding application (FR90.02853, PCT/FR91/00177) filed on even date herewith, describes a process for producing,
Alumino-silicate geopolymers have a tridimensional structure and belong to the category of zeolites and feldspathoids. For these materials it is known that thermal stability is a function of the ratio Si/Al. The higher this ratio, the higher their stability. Therefore, any worker in the field will understand the interest provided by the use of geopolymers of the type
in comparison with